Certain known cable transportation systems comprise a number of transportation units movable between at least two turnaround stations, and normally comprising cars or chairs. A cable transportation system comprising only cars is known as a cable-car, and one comprising only chairs is known as a chair-lift. In recent years, combination cable transportation systems comprising both chairs and cars have also become popular.
Chair-lifts, or any cable transportation system comprising chairs, involve safety issues, to prevent passengers from falling off.
Certain known chair-lift transportation units normally comprise a supporting frame attached to a draw cable; and a chair comprising a bench and a backrest. To prevent passengers from falling off the chair, each transportation unit is equipped with a safety frame hinged to the supporting frame and movable between a closed position and an open position allowing passengers on and off the chair. The safety frame comprises a front bar which, in the closed position, is located over the bench and in front of the backrest, to prevent passengers from falling off.
Some known transportation units comprise locking devices for locking the safety frame in the closed position along the route between the turnaround stations, and only releasing the safety frame along the route inside the turnaround stations.
The safety frame and locking devices of these known transportation units have done a lot to improve the safety of chair-lifts, but concern over passengers falling off still remains, owing to the safety frame and locking devices failing to prevent passengers from slipping off between the bench and the front bar, even when this is in the closed position. Incidents of this sort mainly involve passengers of small build, such as children, on account of the chairs, and therefore the distance between the front bar and the bench, normally being configured for adult passengers of medium build.
Various solutions have been proposed to at least partly solve the problem of passengers falling off the chair.
A first solution, chronologically, provides in fixing safety barriers to the front bar, as shown on page 10, FIG. 16 of the No. 2/1989 issue of Rivista Internazionale delle Funivie magazine, or on page 15, FIG. 6 of the No. 5/1989 issue of Revue Internationale des Téléphériques magazine.
The above magazines are substantially two issues of the same magazine in different languages, and show the same photograph of a chair produced by the Swiss company Von Roll, and wherein the safety barriers comprise brackets fixed to the front bar. Each bracket is located in front of and centrally with respect to a respective passenger seat, and extends between the front bar and the bench and centrally with respect to the passenger seat when the safety frame is in the closed position. In actual use, the safety barrier is located at least partly between the passenger's thighs, to prevent the passenger from falling off.
This technical solution was later taken up by the Swiss company Garaventa in Austrian Patent No. 411,046 B, in which the bracket is fitted in rotary manner to the front bar.
Other solutions proposed by Innova Patent GmbH in European Patent No. 1,721,801 B1 substantially all comprise a safety barrier having a contact surface located under and extending parallel to the front bar, and pressed elastically against the legs of the passenger(s) sitting in the chair.
The safety barriers described in European Patent No. 1,721,801 B1 are characterized by adapting elastically to the passenger's build, but are sometimes expensive to produce, call for careful maintenance, cause a certain amount of discomfort by exerting concentrated pressure on a small area of the passenger's thighs, and may give rise to lateral buckling under combined bending and compressive stress, when the movable member is not guided properly.
Generally speaking, the above-described solutions pose drawbacks in terms of passenger comfort.